Studies will be conducted on the effects of two chemical modifiers on the coupling factor ATPase (CF1) of chloroplasts. One of them is the arginine-specific modifier, naphthylglyoxal; the other is the reactive potential chemical analogue of ATP, 5'-p-fluorosulfonylbenzoyl adenosine. In both of these evidence will be sought for interaction with nucleotide binding sites, in terms of possible displacement of bound nucleotides, inhibition of the light-dependent nucleotide exchange, or alteration of the ADP allosteric inhibition site. Radioactive analogues are available and will be used to trace the particular peptide of the alpha or beta subunit to which each is attached. Attempts will be made to dissociate CF1 into component subunit polypeptides without using SDS, separate them, then reconstitute an active ATPase. The ability to perform hybridization between native and chemically modified subunits will help to pin down the site of action of modifiers. Attempts will be made to see if the high energy state-dependent hydrogen exchange of membrane-bound CF1 is inhibited by blocking off the proton channel with DCCD, or if it is responsive to the general condition of the energized membrane.